Some integrated circuits have a protective overcoat (PO) layer over a top metallization layer containing bond pads, with openings in the PO layer exposing the bond pads. The integrated circuits are fabricated by forming a metal liner, suitable for wire bonding, over the PO layer, extending into the PO layer openings and onto the exposed bond pads. The metal liner over the top surface of the PO layer is subsequently removed by a chemical mechanical polish (CMP) process, leaving the metal liner on the bond pads. The CMP process uses a slurry with abrasive particles and corrosive chemicals to remove the metal liner; the abrasive particles and corrosive chemicals attack the metal liner on the bond pads, causing corrosion of the bond pads and reliability problems for the integrated circuit.
Increasing the thickness of the metal liner increases the cost and complexity of the deposition process and the CMP process, and has not demonstrated desired reduction of damage to the metal liner from the CMP slurry. Adding additional pattern steps or plating processes to protect the metal liner also undesirably increase the fabrication cost and complexity. Using thicker top metal increases the difficulty of patterning and limits the minimum features and line separations.